1. Field of the Invention
The present invention relates to a bearing, a bearing device, and a recording device that are used in a hard disk.
2. Background Art
The hard disk reads and writes magnetic recording data by causing a magnetic head to float and perform a swinging movement across a rotating magnetic disk. An arm having the magnetic head is rotated and supported by a bearing device. With improvement of recording density of the hard disk and improvement of reading and writing speeds of the data, high durability is required in the bearing device that supports the magnetic head. For that reason, in the bearing device for the hard disk, in order to secure durability, grease using a base oil in which a mineral oil is mixed with poly-α-olefin is used (see JP-A-2003-239954).
In general, a floating quantity of the magnetic head is reduced with an improvement of the recording density of the hard disk. When the floating quantity of the magnetic head is reduced, the attachment of foreign matter to the magnetic head leads to reading and writing errors. The foreign matter, not only solid matter, but also oil droplets or the like, causes problems in reading and writing the data.
The grease of JP-A-2003-239954 generates an outgas of a large quantity of aliphatic hydrocarbon based on a composition of the base oil. The outgas of aliphatic hydrocarbon has a problem in that the outgas is condensed on the magnetic disk of the hard disk, is attached as oil droplets, and causes the reading and writing errors of the data. Thus, there are great problems in an improvement of the recording density of the hard disk and an improvement of the reading and writing speeds of the data. Furthermore, in the grease, a phenomenon also occurs where the base oil as well as the outgas becomes oil droplets and is scattered. This is also similarly attached to the magnetic disk in an oil droplet shape and causes the same problem.
The present invention has been made out of consideration of the situations mentioned above, and an object thereof is to provide a bearing, a bearing device, and a recording device that can reduce the reading and writing errors of the data even if foreign matter is attached to the magnetic disk.